A number of techniques are used to perform artificial insemination. Typically, gametes or zygotes are introduced via a catheter into the uterus or a fallopian tube. The medical community is not in complete agreement as to the best location for placement of gametes or zygotes. There is controversy whether uterine or fallopian tube placement is better and, with respect to each, as to the precise location within the uterus or fallopian tube.
One transcervical procedure described by R. Jansen in "Catheterisation of the Fallopian Tubes from the Vagina", The Lancet, Aug. 8, 1987, page 309, utilizes a catheterization system that is inserted through the vagina and cervix, through the uterus and into the fallopian tube to place reproductive cells in the fallopian tube. The system includes an introducing catheter, an obturator, and a transfer catheter. The obturator is used to straighten and stiffen the introducing catheter during insertion. The introducing catheter, stiffened by the obturator, is advanced into the vagina and through the cervix. The distal portion of the introducing catheter is normally curved to assist positioning of the tip at the entrance of the fallopian tube when the introducing catheter is disposed in the uterus. After the distal portion of the introducing catheter is within the uterus, the obturator is withdrawn and the introducing catheter assumes its curved shape. It is manipulated to locate the tip at the entrance to the fallopian tube.
Reproductive cells are loaded into the distal end of the transfer catheter, and the transfer catheter then is passed through the introducing catheter and is advanced into the fallopian tube to a desired position. The cells then are expelled from the transfer catheter by flushing the catheter with a liquid, such as a culture medium, e.g., Hams Solution. Preloading the transfer catheter at its distal end avoids dilution of the reproductive cells which would occur if the cells were delivered through the proximal end of the transfer catheter using a large quantity of flushing fluid.
The foregoing procedure relies on the transfer catheter to force its way through the fallopian tube until the desired position is reached. Much of the fallopian tube normally is in a collapsed condition, however, and manipulation of the loaded transfer catheter within the fallopian tube can cause premature spillage of some of the reproductive cells before the transfer catheter can be advanced fully to the desired position within the fallopian tube. Also, the musculature of the fallopian tube can crush the transfer catheter which may prevent its advance or cause additional spillage of reproductive cells.
Another procedure, as disclosed in U.S. Pat. No. 4,832,681 (Lenck), utilizes a surgical method of installing a catheter through the uterine wall to implant an ovum or zygote in the uterine cavity. The catheter is made of a flexible tube such as silicone elastomer reinforced with a coiled wire. The distal end of the tubing is installed through the uterine wall by advancing it through the vagina, making an incision in the upper portion of the vagina, and advancing the tubing along the outside of the uterus. An incision is made in the uterine wall and the distal end of the tubing then is inserted through the uterine incision to communicate with the uterine cavity. The tubing is relatively large (having an inner diameter of between 2 and 2.5 mm and an outer diameter of between 4 and 4.5 mm) and is unsuitable for insertion within the fallopian tube. The technique of installing the tubing involves the attendant risks and trauma of surgery.
It would be desirable to provide an artificial insemination system usable for both fallopian tube and uterine placement of reproductive cells. Additionally, it would be desirable to provide such a system in which the precise location where the reproductive cells are deposited can be determined. Information as to the actual placement of reproductive cells at varying depths and locations within the reproductive system of the patient may be of importance in connection with subsequent placement of reproductive cells in that patient. It is among the general objects of the invention to provide such a system.